Gas turbo-engines, such as axial flow turbo jet engines, have a compression stage, a combustion stage and a turbine stage. The gas axially traverses these various stages. First of all, it is compressed in the compression stage and then burnt with the fuel in the combustion stage. Finally, it is tapered off in the turbine stage so as to provide work for the rotor and accordingly the thrust produced by the turbo jet engine. The rotor of this stage is equipped with disks.
Now, as the operating temperatures gradually increase inside the turbo jet engine, it is necessary to provide cooling air under pressure to the disks of the rotor of the turbine as these disks are located extremely close to the outlet zone of the combustion chamber and undergo significant cubical expansions. In fact, it is assumed that the technology of the disks of the turbine is determined so as to adjust the cubic expansion of the rotor to that of the stator during the cruising phase so that the performances of the turbo jet engine are kept at their highest level. Accordingly, during the lift-off and/or flight climbing stages with the turbo jet engine functioning at full capacity, the temperatures of the components of the turbines are above the limits imposed by their mechanical behaviour. It is therefore essential to ensure that these situations are avoided and accordingly ensure the cooling of the disks of the turbine by means of sufficiently fresh air.
In this respect, reference may be made to the patent document FR-A-2 557 207 disclosing a cooling system for providing an air pad with a compartment of bearings in a turbo jet engine. In this system, a cold air source is taken from the blower of the turbo jet engine. An under-pressure gas source is taken from the rear stage of the high pressure compressor, this air existing at a high temperature. A heat exchanger is used for cooling this high pressure air with the aid of the cold air taken from the blower.
The object of the invention is to improve the effectiveness of these devices by enabling the system to act on the disks and stator of the turbine, irrespective of the range of capacity of the turbo jet engine, with the aim of keeping the disks and the stator in a relatively restricted temperature range so as to avoid any excessive significant cubical expansions and excess temperatures.
Secondly, there are similar devices distributing the cooling air on the disks of the turbine by using four different pipes so as to intervene on several stages of the turbine.